Peter Zijlstra a écrit :
+static void *get_futex_address(union futex_key *key)
+{
+ void *uaddr;
+
+ if (key->both.offset & 1) {
+ /* shared mapping */
+ uaddr = (void*)((key->shared.pgoff << PAGE_SHIFT)
+ + key->shared.offset - 1);
+ } else {
+ /* private mapping */
+ uaddr = (void*)(key->private.address + key->private.offset);
+ }
+
+ return uaddr;
+}
This will not work for nonlinear vmas, granted, not a lot of ppl stick
futexes in nonlinear vmas, but the futex_key stuff handles it, this
doesn't.
Indeed ! Thanks for pointing me to this.
Since I'm not familiar with vmm, does this code look more correct to you ?
static void *get_futex_address(union futex_key *key)
{
void *uaddr;
struct vm_area_struct *vma = current->mm->mmap;
if (key->both.offset & 1) {
/* shared mapping */
struct file * vmf;
do {
if ((vmf = vma->vm_file)
&& (key->shared.inode == vmf->f_dentry->d_inode))
break;
vma = vma->vm_next;
} while (vma);
if (likely(!(vma->vm_flags & VM_NONLINEAR)))
uaddr = (void*)((key->shared.pgoff << PAGE_SHIFT)
+ key->shared.offset - 1);
else
uaddr = (void*) vma->vm_start
+ ((key->shared.pgoff - vma->vm_pgoff)
<< PAGE_SHIFT)
+ key->shared.offset - 1;
} else {
/* private mapping */
uaddr = (void*)(key->private.address + key->private.offset);
}
return uaddr;
}
Or is there a more direct way to retrieve the vma corresponding to the given
inode ?
Thanks,
--
Pierre
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